Circuit for telephone-exchanqes



(No Model.)

A. S. HIBBARD.

CIRCUIT FOR TELEPHONE EXCHANGES. N0.'274,60Z. tented Mar. 27,1883.

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- scriber is wanted.

UNITED STATES ANGUS S. HIBBARD, OF MILW'AUKEE, WISCONSIN, ASSIGEOR TOTHE WESTERN ELECTRIC COMPANY, OF CHICAGO, ILLINOIS.

CIRCUIT FOR TELEPHONE-EXCHANGES.

SPECIFICATION forming part of Letters Patent No. 274,602, dated March27, 1883.

Application filed J anuury 2, 1883. (No model.)

To all whom it may concern:

Be it known that I, ANGUs' S.'HIBBARD, a citizen of the United States,residing at Milwaukee, in the county of Milwaukee and'State ofWisconsin, have invented a certain new and useful Improvement inTelephone-Circuits for TelephoneExchanges, of which the following is afull, clear, concise, and exact description, reference being had to theaccompanying drawing forming a part of this specification.

The object of my invention is to facilitate the receiving and answeringcalls at the central office of a telephone-exchange.

Severalsystems of signaling have been heretofore employed. In one systemwith which I am familiar each telephone-line is connected from itsspring'jack upon the switch-board to a ground-line including thelistening-operators telephone, in which case the subscriber speaks atonce to the 0perator,who alwaysstands list enin g. On learning whatsubscriber is wanted the operator can ring up said subscriber by sendinga current to his line. The springjacks of the callingand calledsubscribers are then connected together by means of plugs and a flexiblecord, in which should be included the usual clearing-out annunciator. Inother systems now in common use each telephoneline is connected throughits spring-jack and annunciator to ground. The operator, on seeing anannnnciator-shutter fall, inserts one of a pair of plugs into thespring-jack of the line, and thus disconnects the annunciator. By meansof a key the operator first throws a battery to line to inform thesubscriber that his call has been received at the central office, andthen by means of another key the operator connects his telephone to theline of the calling subscriber. The operator now listens to thesubscriber and learns what other sub- Thereupon he inserts the otherplug of the pair in the spring-jack of the called subscriber, and bymeans of another key throws a current to the called subscribers line,who is thus notified by the ringing of his bell. In another system theshutter of the annunciator in a'subscribers line, as it falls,automatically cuts out the annunciator and at the same time connects theline to a normaily-open ground-line including thelistenin goperatorsoutfit.

My system herein-described is an improvement on the systems heretoforementioned; and it consists in akey included between .the spring-jack andannunciator of each line, and a branch circuit between said key and theannnnciator for connecting tothe operators telephone.

In the drawing, which is illustrative of my invention, 1, 2, and 3 aretelephone-lines. a,

b, and c are spring-jack switches, which are placed upon theswitch-board at the central office and operated in the usual manner.

I have'not shown the cords and plugs for connecting the spring-jackstogether, as they are well known. I have placed upon theswitchboard,near the different spring-jacks, the keys or switches d cf. I have alsoprovided connections g hi with a battery, in. The annunciators Z in itare included in the circuits of the telephone-lines, as shown.

I have provided the branches 0 12 q for connecting the telephone-linestothe listening-operators telephone 1*. The circuit of telephoneline 1 maythus be traced to the spring-jack a, and thence to switch cl and throughannunciator l to ground, as shown. When the subscriber sends current toline the shutter of the annunciator is thrown down. The shutter, whenthus thrown down, automatically connects the line to thelistening-operators telephone. listening-operators telephone 4 byshutter of annunciator m at branch p. As soon as the operator sees ashutter fall he answers the call by throwing current to line. Thus key 0is shown depressed, and the battery is is connected to line 2 at branchh. A single impulse is sufficient to inform the subscriber that his callis received at the central oftice. Line 2 is therefore open to theannuncia-tor m and telephone 7 at key 6 only for an instant. Theoperator listens at telephone 7 and finds out what other subscriber iswanted by subscriber ofline2. Supposeit to be the subscriber of line 3.The operator, by depressing key f, sends current to line 3, and thenproceeds to connect spring-jacks b 0 by means of a pair of plugs andcords in the usual manner.

I claim as my invention- 1. The combination, in the circuit of atelephone-line, of a key for answering the sub- Thus line 2 is shownclosed to the I LIOC scriber, included between the spring-jack andannunciator of the line, the battery audits connection, and a branchline between said key and the annunciator, whereby the line may be 5connected to thelistening-operators telephone, substantially as and forthe purpose specified.

, 2. In atelephone-exehange system, the combination of lines 1 2 3 withspring-jacks a b 0, keys cl e f, contacts g h i, battery 70, annuncial0tors l m n, branch connections 0 10 q, and telephone 1", substantiallyas shown and described.

In a telephone-circuit closed to ground through a spring-jack and anannunciator at the central office of a telephone-exchange, the

I 5 combination, with a branch line adapted to be ANGUS S. HIBBARD.

Witnesses:

S. R. KEMPER, GEO. F. RoHN.

